MICRO-TOPO
image by Mike Wirths
When I read Mike Wirth’s email that he was sending an image of Alphonsus and Ptolemaeus I thought it would be a good shot, just like a number of other good shots that LPOD has used. I was wrong. It is good, but like the very best LPOD images, I - and I hope you - learned quite a bit new from studying it. Ptolemaeus is well known as a relatively flat-floor crater with saucers - probably buried craters. This image shows more variation in the micro-topography of the floor that I have noticed before. In the version of the image below (that I strongly enhanced) you can see low relief areas that suggest the fronts of flows - lava flows or ejecta surge flows? The floor of Alphonsus also shows surprises. The eastern side is smooth and crossed by numerous rilles (and notice the volcanic dark halo crater at bottom right) but the west half is covered by textured debris. Even excellent images at higher Sun angles fail to show this rougher floor. Its existence explains why the rilles only exist on the eastern side of the floor: they are buried on the west side. Nobody knew that.
Chuck Wood
Technical Details:
March 8, 2006. 18″ Starmaster dob, 2.5X’s Powermate barlow, R/IR True Tech filter, Infinity 2-2 camera, 150 frames out of 1100 Done in Registax 3 and Photoshop CS/ Images Plus.
Related Links:
Rükl chart 44
Is it just a coincidence that the far western rille in Ptolemaeus appears to line up directly (through the crater wall) onto the edge of this newly discovered debris field on the west side of Alphonsus? I guess the answer might be yes but hey ….
Comment by apollo — April 6, 2006 @ 2:59 am
Apollo - I don’t know. I’ve always thought that the alignment of Ptolemaeus’ rim with Alphonsus’ central ridge wasn’t an accident. Discovery of this debris zone also makes me wonder about the origin of the central ridge. It is the edge of the rough zone so is it associated with it? On the enhanced image it looks continuous with it - the same type of stuff just more of it. And where did the debris come from? It seems to vaguely radiate from the south so it is could be ejecta from Arzachel, or since the effects of Imbrium sculpture are everywhere, is it Imbrium debris? Great new images answer some questions and raise lots of new ones. And keep me excited about the Moon!
Comment by chuckwood — April 6, 2006 @ 5:45 am